PROJECT SUMMARY/ABSTRACT MAIN RESEARCH COMPONENT 1 Alcohol consumption by pregnant women remains a startlingly common occurrence, despite the well-known potential consequences for the health of exposed children. This is true even when alcohol consumption is moderate, leading some to conclude that there is no safe level of alcohol consumption during pregnancy. One of the most reproducible consequences of even low to moderate levels of prenatal alcohol exposure (PAE) is a heightened ethanol preference and consumption in offspring, a phenomenon found in both humans and animal models. Recent evidence from preclinical research has found consistent evidence of a sex-biased effect, with male offspring showing a greater PAE-induced increase in ethanol consumption and preference than females. This effect is observed even when PAE occurs prior to gonadal differentiation (before gestational day 12 in rodents), suggesting that a non-gonadal sex-biasing factor must be responsible. This project tests the hypothesis that genetic differences between males and females (sex chromosome complement and associated differences in expression dosage of X vs. Y chromosome genes) moderate PAE effects. This hypothesis will be tested using Four-Core genotype mice, in which the normal relationship between sex chromosome complement and gonadal sex has been broken; the four core genotypes thus include XX females, XY females, XY males and XX males. We will use this model to systematically test the prediction that XY genotype, irrespective of gonads and gonadally-derived steroids, is associated with heightened PAE-induced escalation of adolescent ethanol intake and heightened anxiety-like behaviors, and that these behavioral effects reflect disturbed inhibitory synaptic signaling via reduced alpha-1-containing GABAA receptor function in the medial central nucleus of the amygdala. Additional studies will test the hypothesis that differential expression of kdm6a - an X chromosome escapee ? contributes to the differential responses of XX and XY individuals to PAE. Collectively, these studies will define the mechanisms underlying the sex-biased response to gestational alcohol exposure and may reveal molecular pathways and neural circuits that confer susceptibility to this common environmental insult with pervasive effects on brain and behavior.